For the Greek Orthodox church Istanbul (or Constantinopouli as they call it) is as important as Rome is to the Catholics.
The head of the Orthodox church, the Patriarch, still lives in a district called Fener bordering on the Golden Horn.
Before the conquest the main patriarchal church was Aya Sofya but, after 1453 when the Ottoman Empire took over the city, the patriarch began a period of nomadic existence moving from one church to another as they were annexed by the conquerors and turned into mosques.
The patriarchate settled on its current site in 1601 although, as can be seen from the photo, the facade was rebuilt as recently as the late 19th century.
The administrative and residential buildings of the patriarchate are huge wooden structures built around the church and recently restored. Security is tight, but anyone looking like a tourist is waved in by the guard on the gate.
Inside the church is heavily ornate, with an imposing iconastasis, silver coffins containing the bodies of long-dead saints, and a fragment of the pillar at which Jesus was whipped en route to his crucifixion which is shown in our second photo.
If you haven’t visited a Greek Orthodox church this is a good one to start with – and compare the atmosphere to the local parish church in the UK.